They don't need do any of that, what are you talking about? They just need to score more point than their opponents do in any particular game.
Look at 2018 Northwestern, they went 8-1 in the B1G
AVG 24.2 PPG and allowed per game 23.2 PPG.
Iowa 2018
Avg 31.2 PPG and allowed 17.8 PPG
That's true but it is the same as number of games you win. The closer you get to perfection the more every little thing matters. One crappy call against you that keeps a drive alive can be the difference between going 8-1 or 9-0.
Our defense has room to improve, I'm not denying that, but they were pretty good. They were probably better than 6-3, but they were not 9-0 good. Our offense was probably 3-6 maybe 4-5 good. There is no arguing that if our defense can maintain the current level and we put up more points (it's easier for our offense to jump up 40 spots then for our defense to jump up 3).
If our defense can maintain or get better, I would then expect the dynamic to shift in 21 because a whole bunch of them are going to be getting paid on Sundays and the offense is going to need to pick up the slack. But never say never, because Phil has shifted into a time where he is capable of reloading.